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Double-paned windows are all about efficiency. These glass assemblies feature two panes of glass sandwiched over a metal frame. Between the panes is an inert gas that prevents heat transfer and helps the glass insulate the home. If one of those panes cracks, the gas escapes, and the window is inefficient. When a homeowner called general contractor Tom Silva for just this issue, he knew who to call to get the window repaired. Here’s how it went.
Learn about the cost of replacing double-pane windows in our in-depth article.
Three Types of Repairs for Double-Pane Windows
There are three types of repairs for broken double-pane windows. The first repair involves replacing the entire window, from the frame to the sashes inside. This is expensive and labor-intensive. The second option is to order a replacement sash, which is simple, but not all manufacturers offer this.
The third option is to have a custom glass assembly built specifically for the window and replace the broken glass. A window contractor will take measurements and order the window assembly, which usually takes a few weeks to receive. This is economical, but sometimes not possible—it depends on the type of window in question, but the window contractor will be able to tell right away if this is a possibility.
Replacing the Glass
In order to get a glass assembly to fix the window, a contractor must come to the home and look at the broken glass. They’ll inspect whether or not the glass can be replaced and then take measurements of the overall height, width, and thickness of the glass. They’ll then order a replacement glass assembly from a window manufacturer.
At the factory, the measurements are entered into a glass-cutting machine, which will cut the panes to height and width. Next, a frame-bending machine prepares a frame. The glass is then cleaned thoroughly, sandwiched over the frame with an adhesive on its edges, and the assembly is pumped with inert gas. Finally, the panes are pressed firmly together before a worker applies a thick bead of sealant around the outside of the glass.
How to Install Window Glass
Installing the glass is a breeze, but it’s important to be careful with broken glass. We suggest wearing rubber cut-resistant gloves to prevent any accidents.
- Start by removing the sash from the window and placing it broken side down on a cloth.
- Use a pry bar and rubber mallet to remove the window stops holding the window into the frame.
- Use a utility knife to cut the sealant holding the glass into the frame (the opposite side from the removable window stops. Be careful of the broken glass and be sure to cut all the way through the sealant on all four sides.
- Carefully turn the window sash over so the broken side is down. Carefully press the broken window assembly out of the frame. Clean up the edges around the sash to allow for a good seal.
- Squeeze caulk around the inner perimeter of the sash, where it comes in contact with the glass assembly. Apply a thick bead, but don’t apply so much that it will squeeze out and dry on the glass.
- Lift the new glass assembly up and carefully place it into the bead of caulk around the interior edge of the window. Press down firmly and then reinstall the window stops with a rubber mallet.
- Replace the window in the opening and reconnect any of the hardware that typically holds it in place. Secure the window and allow the sealant to cure for 48 hours before cranking the window open or closed.
Resources
Tom works with a glass specialist to repair a cracked double-pane window. Tom travels to the glass manufacturer to see how the replacement glass is produced.
To get started, the specialist measures the width and length of the glass with a tape measure.
An insulating glass caliper is used to measure the thickness of the glass. Measurements are sent to a glass manufacturer.
To replace the broken glass, start by removing the sash and laying it out on a flat surface. To loosen up the trim use a sharp scraper blade and remove it with a pry bar and rubber mallet.
To remove the glass from the frame, use a sharp blade to cut the silicone seal.
Once the glass is removed, apply a new layer of silicone to set in the new glass pane. Use a small rubber mallet to tap the trim back in place, sealing in the glass.
Wear safety glasses and work gloves whenever working with glass.
Assistance and materials were provided by Banner Glass Shellmar and Thermal Seal Insulating Glass Inc., Uxbridge, MA.
